In this application for a level I Research Scientist Development Award a program of research in the developmental psychopathology and differential diagnosis of the severe neuropsychiatric disorders of early onset is proposed. Specific studies include a longitudinal investigation of children with deficits in social communicative competence and an investigation of factors influencing negativistic behavior in pervasively impaired children. A unique feature of the proposal is the careful coordinated study of cognitive, communicative, and social development in such children with the aim of establishing more specific syndrome clusters. Infants participating in the longitudinal study will receive through evaluations and participate in structured observations designed to provide measures of social-communicative competence. As children are followed longitudinally the relation of early patterns of functioning can be traced as they become entrained in later development. New mehtods of assessment and more rigorous diagnostic criteria can then be proposed. Additional experimental protocols can be developed over the course of the award. The proposed award will enable the applicant to receive additional research training at Yale and other centers. The training program, designed in consultation with the research sponsor (Dr. Cohen) and the research advisor (Dr. Zigler) emphasizes advanced work in research methods, statistics, assessment methods, and cognitive, linguistic and social development. Additionally the applicant would receive special training in psychological and biological research with clinical populations. The award would significantly enhance the applicant's contributions to academic child psychiatry.